Rodolfo Dirzo (Cuernavaca, Mexico, 1951) completed a BSc in Biology at the Universidad Autónoma del Estado de Morelos (Mexico) then went on to obtain an MSc and PhD from the University of Wales (United Kingdom). Between 1980 and 2004 he held various teaching and research positions at the National Autonomous University of Mexico (UNAM), serving as a professor, Director of the Los Tuxtlas Biological Station and Chair of the Department of Evolutionary Ecology. In 2004 he joined the faculty at Stanford University, where he is currently Bing Professor in Environmental Science, Professor of Earth System Science, Senior Fellow at the Woods Institute for the Environment and Associate Dean for Integrative Initiatives in Environmental Justice. Dirzo has also taught in Argentina, Brazil, Canada, Chile, Colombia, Costa Rica, Nicaragua and Puerto Rico.
Since Rodolfo Dirzo realized the big impact humans were having on plant and animal ecology and evolution, he has focused his career on the study of biodiversity and ways to preserve it. By analogy with deforestation, in 1991 he came up with the term “defaunation” to refer to the imbalance entailed by the absence of animals.
A key contribution by the awardee has been to detect the cascading effect produced when a species population becomes extinct. That is why he sustains that it is not just species disappearances we have to worry about, but the extinction of species populations and, above all, species interactions, which should accordingly be a core focus of conservation actions. If we eliminate, for example, large vertebrates such as elephants, giraffes or zebras from a savannah in Africa, plants at ground level will grow much more, soil compaction will lessen and fruits and seeds will fall from the trees without being eaten. But also smaller animals like rodents will take advantage of this circumstance and so will the pathogens they carry which, in turn, could be transmitted to humans.
Dirzo lists five key factors that drive defaunation: land use change, the overexploitation of resources, pollution, the introduction of invasive species, and climate change. All of these factors are related, the awardee contends, which is why the problem of mitigating biodiversity loss is so complex.